KR20090070320A - Method of presuming a temperature of at least one part of an engine combustor units using a thermometric device - Google Patents

Abstract

A temperature measuring method for an engine combustor is provided to measure the temperature of the parts of the combustor easily by mounting a thermometric device on the combustor parts. A temperature measuring method for an engine combustor comprises a step of manufacturing a thermometric device by using a thermometric material, a step of mounting the thermometric device on at least one of the parts of the engine combustor, a step of taking a trial driving of the engine, a step of separating the mounted thermometric device and measuring the hardness of the thermometric device, and a step of comparing the measured hardness with the temperature-hardness graph of the thermometric device material to estimate the temperature applied to the thermometric device in the combustion chamber. The thermometric device is made of high-carbon steel or high carbon alloy steel containing carbon more than 0.5 weight%.

Description

Method of presuming a temperature of at least one part of an engine combustor units using a thermometric device}

The present invention relates to a method for estimating the temperature of an engine combustion chamber using a component having a thermometric characteristic, and in particular, to manufacture a thermometric component separately and to mount it in one or more places in the engine combustion chamber and perform a test operation. And a method of estimating the maximum temperature inside the combustion chamber by the change in hardness thereof.

In general, a combustion chamber of an engine using fuels such as diesel, gasoline, and gas (CNG, LPG) is a space in which a cylinder head, a cylinder liner, an intake / exhaust valve, an intake / exhaust valve seat insert, and a piston are mounted. In such a combustion chamber, a mixed gas of air and fuel is exploded to create an atmosphere of high temperature and high pressure. In this case, the materials surrounding the combustion chamber are used in harsh environments where they move in a high temperature state.

Hereinafter, cylinder heads, cylinder liners, intake / exhaust valves, intake / exhaust valve seat inserts, pistons, and the like, which are components related to the formation of a combustion chamber, a space in which the fuel is burned, are collectively referred to as "combustion chamber components".

Typically, in a high temperature and high pressure environment, materials cause deterioration of mechanical properties, so it is necessary to measure at what temperature conditions the parts constituting the actual combustion chamber operate for engine design, maintenance, and the like. When the temperature is measured, it is possible to perform an improvement of adjusting the combustion chamber temperature to an appropriate level by selecting and applying a high temperature material suitable for the condition or adjusting combustion conditions based on the measured temperature.

Conventionally, a method using a thermocouple has been mainly used as a method of measuring the temperature of a material. However, if the thermocouple is to be applied to the materials constituting the combustion chamber, since the thermocouples must be installed at various locations in the combustion chamber due to the characteristics of the combustion chamber having different temperatures at each position, the temperature inside the combustion chamber is actually used by using a thermocouple. It is impossible to confirm.

In particular, the engine piston reciprocates at high speed during engine operation, and slides in contact with the inner wall of the cylinder, so it is practically impossible to measure the actual temperature by mounting a thermocouple.

One way to solve this problem is to use a thermometric material. Thermometric material has a property that the hardness changes with the change of temperature, there is a method of measuring the temperature change or the temperature history by using the correlation between the temperature and the hardness of the thermometric material.

According to this method, after manufacturing a part having the same shape and size as the actual part by using a thermometric material, and applying it as a real vehicle as one of the engine parts, the technology to estimate the temperature according to the change in hardness by measuring the hardness This has been proposed. However, in order to apply the above method, since the thermometric material is heat-treated to make a high hardness material for the initial hardness measurement before the temperature estimation test, it is processed into the actual engine part using the heat-treated thermometric material. It is not easy to do, and the unit price is high.

In addition, for example, in the case of a fast moving part such as a piston, the inertia force control by weight should be considered. That is, when the piston having the same shape and size as the actual piston is manufactured by using a thermometric material, and the hardness is measured after the actual vehicle is applied, the inertia force must be taken into consideration. Pistons of the same thermometric material shall be manufactured to the same weight and weight. However, a common material used in conventional pistons is an aluminum alloy, and thermometric materials having similar weight characteristics to those of aluminum alloys are currently unknown. Therefore, it can be said that it is impossible at present to measure the temperature of the piston part of a combustion chamber by making a temperature measuring piston using a thermometric material.

Meanwhile, a method of estimating a temperature by measuring a change in hardness of the plating layer formed on the combustion chamber component by driving an engine after forming a plating layer using a material having thermometric properties on some of the components forming the combustion chamber is also proposed. It is.

However, the temperature estimation method using plating has a problem that is difficult to apply to a large structure such as a cylinder head, but having a very complicated structure. In addition, if the plating is applied to a component that causes wear, such as a piston skirt or a cylinder inner wall, the plating layer may be lost due to wear during operation, which is not suitable for a long time operation test.

In order to solve the above problems, in the present invention, the thermometric component is manufactured separately for the combustion chamber temperature measurement, and then mounted on at least one of the combustion chamber components constituting the combustion chamber to change the hardness of the thermometric component after the test operation. By measuring, it is possible to estimate the maximum temperature applied to the corresponding combustion chamber components during combustion.

Accordingly, the present invention provides a step of manufacturing a thermometric component capable of temperature estimation, mounting the thermometric component to any one of combustion chamber components, and performing a test operation; It provides an engine combustion chamber temperature estimation method comprising the step of estimating the temperature by measuring the.

Specifically, the engine combustion chamber temperature estimation method according to the present invention comprises the steps of manufacturing a thermometric component using a thermometric material, mounting the thermometric component in at least one of the components of the engine combustion chamber, and Performing a test run, removing the mounted thermometric part after the test run, and measuring hardness; and comparing the hardness of the thermometric part after the test run with a temperature-hardness graph of the thermometric part material. Estimating the temperature applied to the thermometric part in the engine combustion chamber.

In the present invention, cylinder heads, cylinder liners, intake / exhaust valves, intake / exhaust valve seat inserts, pistons, and the like, which are components related to the formation of the combustion space of the combustion chamber, are collectively referred to as "combustion chamber components".

On the other hand, in order to more accurately estimate the temperature in the present invention, after manufacturing the thermometric part using the thermometric material, the initial hardness of the thermometric part is measured in advance, so that the hardness and the thermometric part of the thermometric part after the test run. The initial hardness value may be usefully used in the process of comparing the temperature-hardness graph of the materials.

On the other hand, according to an example of the present invention, a carbon-containing high carbon steel or high carbon alloy steel containing 0.5% by weight or more of the material may be used as a material for manufacturing the thermometric part, and the initial Vickers hardness of the thermometric part may be 700 or more. Can be.

According to another example of the present invention, the thermometric component may contain 0.5 to 2.0% by weight of carbon and 0.8 to 2.5% by weight of chromium.

On the other hand, even if the thermometric component is mounted to the combustion chamber component it will be desirable to maintain the same weight and surface state of the component.

In addition, it is desirable that the thermometric part be as small as possible to be mounted in as many positions as possible.

In addition, the thermometric component is preferably manufactured to have a structure that is easy to install and remove so that the temperature can be easily estimated through test operation and hardness measurement.

According to an example of the present invention, the thermometric component may be manufactured in a thread form and mounted on at least one of the components of the engine combustion chamber. According to a preferred example of the invention, the thermometric part can be mounted to a piston. In addition, when the thermometric part is mounted to the piston, it may be mounted to various parts of the piston as shown in FIGS. 3A and 3B.

According to another example of the present invention, the material of the thermometric part has an initial hardness of Vickers hardness of 700 or more through predetermined heat treatment, and has a hardness of Vickers hardness of 400 or less when exposed to high temperature of 600 ° C or higher, and further, A Vickers hardness of 50 or more changes per temperature change can be used.

According to an example of the present invention, the material of the thermometric part of the present invention can be used to decrease the hardness in proportion to the rise in temperature.

When the thermometric component according to the present invention is used, the temperature applied to the combustion chamber component can be easily estimated because the thermometric component can be mounted on the component of the combustion chamber in a relatively simple manner. There is an effect that the design for estimating the combustion chamber temperature or the manufacturing time and cost of the apparatus or equipment can be innovatively reduced.

Hereinafter, with reference to the embodiment and the drawings will be described in more detail the configuration of the present invention.

As described above, in the present invention, the combustion chamber components are previously known to include intake and exhaust valves, intake and exhaust valve seat rings, piston and piston rings, cylinder heads and cylinder liners, and the like.

First, a thermometric part used in the present invention is manufactured.

According to an example of the present invention, as a material for manufacturing the thermometric part, a high carbon steel having a carbon content of 0.5% or more may be used as a material having high hardness through heat treatment.

On the other hand, a small amount of alloying elements such as chromium, molybdenum, manganese and nickel may be further added to the high carbon steel material in order to enhance the heat treatment effect. In this case, the material may be referred to as high carbon alloy steel. In the present invention, the high carbon steel material and the high carbon-containing steel material are not particularly distinguished.

According to an example of the present invention, the high carbon steel material includes iron (Fe), which is a basic material, and C (carbon), Si (silicon), Mn (manganese), P (phosphorus), S (sulfur), and Cr (chromium). It is possible to further include a material.

According to another example of the present invention, high carbon alloy steel containing iron may be used as a thermometric material in the range of 0.5 to 2.0% by weight of C (carbon), 0.8 to 2.5% by weight of Cr (chromium). If C (carbon) is 0.5 wt% or less, the hardness is low, and if it is 2.0 wt% or more, the hardness is high, so that processing is difficult. In addition, if Cr (chromium) is less than 0.8% by weight, the hardness is low, so it may be easily worn or damaged at high temperatures, and if it is more than 2.5% by weight, the hardness is high, making it difficult to process thermometric parts.

The size or shape of the thermometric component is not limited and may be variously manufactured and used by those skilled in the art as needed. Therefore, it is also possible to separately manufacture and use a thermometric part of an appropriate size for each part of each combustion chamber.

However, since the thermometric component is mounted to the combustion chamber component, it may be desirable to manufacture the thermometric component so as not to affect the overall appearance of the combustion chamber component even after the thermometric component is mounted on the combustion chamber component. will be. To this end, according to an example of the present invention, the length of the thermometric part is limited to within 10mm, within 5mm in diameter. If the size of the thermometric part is larger than the above dimensions, it may be difficult to mount it on parts such as valve seat inserts and piston skirts having a small thickness, and if the thermometric part is manufactured too small, it may be difficult to manufacture and may be mounted / demounted. It is also difficult, and hardness measurement is not easy in the future. Thus, it would be convenient to fabricate the thermometric part within the dimensions.

In addition, according to an example of the present invention, the thermometric part may be easily installed and removed from the combustion chamber component, and the outer circumferential surface thereof may have a thread shape so that no escape occurs during the test. In order to mount such thermometric components to the combustion chamber components, it will be necessary to form mounting grooves in the combustion chamber components in advance.

Thermometric parts manufactured in the above dimensions and shapes are subjected to a hardening heat treatment to ensure high initial hardness. According to one example of the invention, the hardness after heat treatment is preferably Vickers hardness 700 or more.

In consideration of the errors occurring during the hardness measurement, the higher the initial hardness, the greater the decrease in hardness due to the heat treatment effect, and thus, the accuracy of the temperature estimate using the hardness-temperature relationship graph will be improved. Therefore, according to an example of the present invention, when the hardening heat treatment is performed, the hardness after hardening of the high carbon steel or the high carbon alloy steel material, which is the thermometric material, may be limited to the Vickers hardness of 700 or more.

The heat treatment method may apply a conventional hardening heat treatment method for high carbon steel and high carbon alloy steel. Since the hardening heat treatment method for the said material requires a well-known technique, detailed description of the method is abbreviate | omitted.

The hardened heat treated high carbon steel and high carbon alloy steel have a low hardness due to a tempering effect when exposed to high temperature. The decrease in hardness for the tempering effect of the material is generally linearly proportional to the temperature increase. 1 is a graph showing the temperature-hardness relationship of a high carbon alloy steel according to one example of the present invention.

Referring to FIG. 1, it can be seen that the high carbon steel and the high carbon alloy steel hardened and heat treated according to the present invention can be usefully used as a thermometric material because the hardness value decreases almost linearly with the heat treatment temperature.

That is, it is preferable that the properties of the thermometric material change proportionally (linearly) in accordance with the tempering temperature change, and the hardened heat treated high carbon steel and the high carbon alloy steel according to the present invention sufficiently satisfy these characteristics (Fig. 1). Here, FIG. 1 is a hardness measured using a micro vickers, and the load is 300 gf.

The thermometric parts are then mounted and commissioned in the actual engine combustion chamber.

Then, after removing the thermometric part, the hardness is measured using a Vickers microhardness meter, and the hardness value is determined according to the tempering temperature of the thermometric material, which is a temperature-hardness graph of the thermometric part shown in FIG. Compared with the "hardness change" graph, one can estimate the maximum temperature applied to the combustion chamber components inside the combustion chamber.

<Example 1>

Thermometric parts were fabricated using high carbon alloy steel materials.

The chemical composition of the high carbon alloy steel material is shown in Table 1 below.

Chemical Composition of Materials for Thermometric Parts (Unit: wt%) C Si Mn P S Cr Fe 0.10 0.25 0.35 0.02 0.02 1.45 Remaining amount

The shape of the manufactured thermometric part is as shown in FIG. 2. Specifically, the dimensions of the thermometric part was 4mm in diameter, 6mm in length, and the outer circumferential surface was processed to facilitate the removal of the thread.

Curing heat treatment was performed on the parts manufactured in the above dimensions to finally produce a thermometric part. Curing heat treatment was oil-cooled after holding for 30 minutes at 840 ℃.

The above thermometric parts were mounted at various positions of the piston. 3A and 3B show well where the thermometric part is mounted on the piston. For reference, FIG. 3A is a view showing a top surface of a piston on which a thermometric part is mounted, and FIG. 3B is a view showing a longitudinal section of a piston on which a thermometric part is mounted.

In Figs. 3A and 3A the numbers indicate where the thermometric parts are mounted.

After the engine was assembled using the piston equipped with the thermometric parts, the assembled engine was operated for 180 minutes to perform a real vehicle test. Then, the thermometric parts were removed and the hardness was measured to estimate the temperature.

The temperature change measurement results are shown in FIG. 4.

As can be seen from the above results, when using the thermometric component of the present invention, it is possible to estimate the temperature applied during combustion for various parts of the piston.

Although the present invention described above is limited to the above-described embodiments, the scope of the present invention is not limited thereto, and it can be easily implemented by those of ordinary skill in the art. It is apparent that modifications to the extent possible belong to the technical idea of the present invention.

1 is a graph showing the temperature-hardness relationship of high carbon alloy steel according to an example of the present invention.

2 shows the shape and dimensions of a thermometric part according to an example of the invention.

3a shows a top view of a piston on which a thermometric component is mounted. In FIG. 3A the numbers indicate the positions where the thermometric parts are mounted.

3b shows a longitudinal section of a piston in which a thermometric component is mounted.

4 is a graph showing an example of estimation of an engine combustion chamber temperature measured using a thermometric component according to an example of the present invention.

Claims (5)

Manufacturing a thermometric part using the thermometric material; Mounting the thermometric part to at least one of the components of an engine combustion chamber; Test driving the engine; Measuring hardness of the thermometric part by removing the mounted thermometric part after the test operation; And Estimating a temperature applied to the thermometric part site in the combustion chamber by comparing the hardness and the temperature-hardness graph of the thermometric part material after the test operation. The method of claim 1, wherein the thermometric component is made of a carbon-containing high carbon steel or a high carbon alloy steel material of 0.5 wt% or more, and has an initial Vickers hardness of 700 or more. 3. The method of claim 2, wherein the thermometric component contains 0.5 to 2.0 weight percent carbon and 0.8 to 2.5 weight percent chromium. The method of claim 1, wherein the thermometric part is manufactured in a thread form and mounted to at least one of the components of the engine combustion chamber. The method of claim 1, wherein the thermometric part is mounted to a piston.

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